In vitro fermentation of cereal dietary fibre carbohydrates by probiotic and intestinal bacteria

A range of probiotic and other intestinal bacteria were examined for their ability to ferment the dietary fibre carbohydrates β‐glucan, xylan, xylo‐oligosaccharides (XOS) and arabinoxylan. β‐Glucan was fermented by Bacteroides spp and Clostridium beijerinckii but was not fermented by lactobacilli, bifidobacteria, enterococci or Escherichia coli. Unsubstituted xylan was not fermented by any of the probiotic bacteria examined. However, many Bifidobacterium species and Lactobacillus brevis were able to grow to high yields using XOS. XOS were also efficiently fermented by some Bacteroides isolates but not by E coli, enterococci, Clostridium difficile, Clostridium perfringens or by the majority of intestinal Lactobacillus species examined. Bifidobacterium longum strains were able to grow well using arabinoxylan as the sole carbon source. These organisms hydrolysed and fermented the arabinosyl residues from arabinoxylan but did not substantially utilise the xylan backbone of the polysaccharide. Arabinoxylan was not fermented by lactobacilli, enterococci, E coli, C perfringens or C difficile and has potential to be an applicable carbohydrate to complement probiotic Bif longum strains in synbiotic combinations. © 2002 Society of Chemical Industry     

Utilisation of corn (Zea mays) bran and corn fiber in the production of food components

The milling of corn for the production of food constituents results in a number of low‐value co‐products. Two of the major co‐products produced by this operation are corn bran and corn fiber, which currently have low commercial value. This review focuses on current and prospective research surrounding the utilization of corn fiber and corn bran in the production of potentially higher‐value food components. Corn bran and corn fiber contain potentially useful components that may be harvested through physical, chemical or enzymatic means for the production of food ingredients or additives, including corn fiber oil, corn fiber gum, cellulosic fiber gels, xylo‐oligosaccharides and ferulic acid. Components of corn bran and corn fiber may also be converted to food chemicals such as vanillin and xylitol. Commercialization of processes for the isolation or production of food products from corn bran or corn fiber has been met with numerous technical challenges, therefore further research that improves the production of these components from corn bran or corn fiber is needed. Published 2010 by John Wiley & Sons, Ltd.     

低聚木糖的脱色工艺

研究了 10种不同的活性炭和 6种阴离子交换树脂对低聚木糖溶液的脱色效果 ,并求得了它们的吸附等温线 .结果表明 ,糖用活性炭AC2 和AC6 及阴离子树脂D30 1 G对低聚木糖溶液具有较好的脱色效果 ,对糖液色素的吸附符合Freundlich方程 .在进一步的扩大试验中 ,采用AC2 、AC6 (10 %AC2 + 3%AC6 ,用量相对于糖液的干固物质 )和阳离子树脂 732、阴离子树脂D30 1 G的组合 ,低聚木糖溶液的总脱色率达到 95 .3% ,总的糖损失为 2 0 % .     

低聚木糖的生产及应用研究进展

低聚木糖是功能性低聚糖类中功能较好的一种 ,工业应用范围广泛。文章着重介绍了低聚木糖的理化特性、生产以及应用等方面的国内外研究进展 ,并简要介绍了课题组的一些研究工作进展。     

新生磷酸钙对低聚木糖的脱色规律

研究表明，新生磷酸钙对酶解低聚木糖液中所含色素的吸附率高于对低聚木糖的吸附率，对低聚木糖的吸附率随氢氧化钙用量呈直线上升的趋势。以5.0g/L氢氧化钙对24.0g/L的酶解低聚木糖液进行脱色时，脱色率可达87．1％，低聚木糖的损失率为10．0％。酶解低聚糖中可被新生磷酸钙所吸附的色素物质可能是线性或平面分子，新生磷酸钙对色素的等温吸附属于Langmuir型等温吸附。     

制备色谱分离纯化小麦麸皮低聚木糖的工艺优化

研究以强酸性阳离子交换树脂为吸附介质,利用色谱技术对低聚木糖液进行分离纯化。通过对不同吸附介质的筛选及不同因素对强酸性阳离子交换树脂对低聚木糖分离效果的影响,确定最适的分离介质及最佳的分离条件。结果表明,强酸性阳离子交换树脂对低聚木糖液具有较好的分离效果,优化后最佳的分离条件为流速1.5 m L/min、进料量为10 m L、进料浓度为30 g/100 m L、操作温度为70℃,低聚木糖液的纯度为95.68%,低聚木糖与单糖实现了较好的分离,为进一步工业化分离低聚木糖奠定了理论基础。     

采用蒸汽爆破技术制备木低聚糖的尝试

初步探讨了用蒸汽爆破玉米秸秆技术制备木低聚糖和可溶性木聚糖的工艺条件。结果发现,采用１．６ ＭＰａ 和２．０ ＭＰａ 的蒸汽压,维压５ ｍ ｉｎ,可以使戊聚糖较好地溶出,戊聚糖回收率达４０．０％ ～５９．０％ 。其中,低聚糖得率达３６．０％ ～５９．０％ 。在２．０ ＭＰａ的压力条件下,加水有利于戊聚糖的溶出,缓解聚糖的降解。     

Hydrothermal processing of rice husks: effects of severity on product distribution

BACKGROUND: Treatment in aqueous media (hydrothermal or autohydrolysis reactions) is an environmentally friendly technology for fractionating lignocellulosic materials. Rice husks were subjected to hydrothermal processing under a variety of operational conditions to cause the selective breakdown of xylan chains, in order to assess the effects of reaction severity on the distribution of reaction products. RESULTS: The effects of severity (measured by the severity factor, R₀) on the concentrations of the major autohydrolysis products (monosaccharides, xylo‐ and glucooligosaccharides, xylooligosaccharide substituents, acetic acid, acid‐soluble lignin and elemental nitrogen) were assessed. The interrelationship between the severity of treatment and molecular weight distribution was established by high‐performance size‐exclusion chromatography. Selected samples were subjected to refining treatments as ethyl acetate extraction and ion exchange for refining purposes, and the concentrates were assayed by high‐performance anion‐exchange chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. CONCLUSIONS The protein equivalent of the products present in liquors accounted for 43 to 51% of the protein present in the raw rice husks. The concentrations of glucose (derived from starchy material) and arabinose (split from the xylan backbone) were fairly constant with severity. Even in treatments at low severity, high molecular weight compounds derived from xylan accounted for a limited part of the stoichiometric amount. Operating under harsh conditions, about 50% of the total xylan‐derived compounds corresponded to fractions with a degree of polymerization (DP) < 9. After refining, saccharides accounted for more than 90% of the non‐volatile components of the sample. The refined products showed a series of xylose oligomers up to about DP 13, and a series of acetylated xylose oligomers up to about DP 15. Copyright © 2008 Society of Chemical Industry     

Diafiltration process on xylo‐oligosaccharides syrup using nanofiltration and its modelling

This work presents a theoretical study of the diafiltration and concentration processes on xylo‐oligosaccharides (XOs) syrup using nanofiltration (NF). In our previous study of the separation performance of the NF process on XOs syrup, the models of flux (J_v) and observed retention (R_obs) of an NF membrane have been established. In the present study, these models were employed to construct the balance equations of syrup volume and XOs concentration in a feed tank. In experiments, the constant‐volume continuous diafiltration (CVCD) and the discontinuous diafiltration processes were implemented. In CVCD simulation, the flux curve predicted by the model agreed well with the experimental data. In discontinuous diafiltration simulation, the calculated total content of XOs was 94.5%, which was about 1.5% less than the experimental result (96.11%) given by discontinuous diafiltration operation on a XOs syrup with initial XOs content 83.5%.